Friction drive means



April 15, 1958 H. R. BILLETER FRICTION DRIVE MEANS Original Fild Sept.30, 1952 5 Sheets-Sheet l April 1958 H. R. BILLETER 2,830,469

FRICTION DRIVE MEANS Original Filed Sept. 30, 1952 5 Sheets-Sheet 2 IN VEN TOR.

April 15, 1958 H. R. BlLLE'l 'ER 2,830,469

FRICTION DRIVE MEANS Original Filed Sept. 30, 1952 5 Sheets-Sheet 4 IN VEN TOR.

April 15, 1958 H. R. BILLETER ,830,

FRICTION DRIVE MEANS Original Filed Sept. 30, 1952 5 Sheets-Sheet 5 Q312 INVENTOR.

eny%berlffiilleler; 316' FRICTION DRIVE MEANS Henry Robert Billeter,Highland Park, 11]., assignor to Ammco Tools, Inc., North Chicago, 111.,a corporation of Illinois Original application September 30, 1952,Serial No. 312,345. Divided and this application September 14, 1953,Serial No. 379,837

20mm. or. 74-691) This invention relates to'feedingmechanisms and has.

to do more particularly with a power driven feeding mechanism having acontinuously variable speed ratio between the input and theoutputjelements.

An object of the present invention is to provide an improved feedingmechanism.

lCc

A further object is to provide novel power transmitting mechanism whichby virtue of its construction is adapted to simple servicing operations.

A still further object is to provide a variable speed power transmittingmechanism of mechanical nature, including slippage means interposedbetween the input and output elements, in which the slippage meansincludes constantly rotating elements, whereby when slippage occurs,-the rotating elements do'not wear out of true shape 'or otherwise wearin such manner as to cause misshaping of the elements. 1 '1 Otherobjects and advantages will be apparent upon reference to the followingdetail description taken in conjunction with the accompanying drawings,in which Figure 1 is a plan view of a lathe embodying the feed of thepresent invention;

Fig. 2 is an enlarged, vertical longitudinal sectional I view of thelathe of Fig. 1, taken on line- 2-2of Another object is to provide afeeding mechanism, the 7 speed ratio of which is continuously variable.

, A further object is to provide a power transmitting mechanism ofmechanical nature" capable of continuously variablespeedhratio betweenthe input and output elements.

A still furtherobject is to provide variable speed feed means capable ofmaintaining. constant speed ratio between its input and output elementsdespite changes in temperature to which it is subjected.

Another object is to provide variable speed feed means having rotatableinput and output shafts, in whichthe torque on the output shaft remainsconstant in an speed ratios between the shafts.

Still another object is to provide variable speed feed means havingrotatable inputand output shafts in which the torque on the output shaftremains constant in all speeds thereof, thereby enabling the use ofsafety release means operative for releasing at any predeterminedsetting regardless of the rate of speed of the output shaft. A furtherobject is to provide a mechanical variable speed feed means having aninput shaft and an output shaft, utilizing differential gear drivebetween the input shaft and the output shaft.

Another object is to provide novel variable speed power transmittingmechanism of mechanical nature that is smooth in operation in andthrough all speeds within its range. f a

A still further object is to provide mechanical variable speed powertransmitting mechanism, having an input shaft and an output shaft, anddifferential gearing interposed between the shafts,'in which slippagemeans is included for controlling the differential gearing, in anarrangement in which the slippage means also provides a safety releasefeature, and in which spring means having a fiat deflection curve isutilized for controlling the slippage means, whereby the reactionforcenecessary for causing slippage of the slippage means is constant for allspeeds of the output'shaft. a

Another object is to providemechanical variable speed power transmittingmechanism, having an input shaft and an output shaft, differentialgearing between the shafts, and slippage means for controlling thedifferential gearing, wherein resistance encountered in the rnechanismis utilized for aiding the' drive of the output element. r v

' Still another, objectis to provide a mechanicalvariable speed powertransmitting mechanism .having an input element and anoutput element,and having safety release means including mutually rotatable,interengaging friction elements arranged for slippage therebetweenwithout misshaping or otherwise impairing the elements? Fig. 1

Fig. 3 is a transverse vertical sectional view takenon line3-3ofFig.1; fFig. 4 is an enlarged transverse vertical sectional view of the feedmechanism, taken on line 4-4 of Fig. land Fig. 7;

Fig. 5 is a fragmentary view of the clutch for the feed means orientedas if taken on line 5--5 of Fig. 6, and with the clutch shiftersuperimposed thereon;

Fig. 6 is a sectional view taken on a staggered line 66 of Fig. 4; andFig. 7 is a view taken on" line 7--7 of Fig. 4showing the drivenfriction disc displaced from its normal position and shown in dot-dashlines. a

For the purposes of illustration the feed mechanism of the presentinvention is described in connection with a lathe in which it maybe-incorporated but it will be understood that the feed mechanism iscapable of more general application and the invention is not limited toapplication to a lathe. The lathe herein'referred to is disclosed andclaimed in my copending application Ser. No. 312,345, filed September30, 1952 of which the present application is a division.

The lathe includes frame or stand 12 which is hollow and supports all ofthe other parts of the lathe and'includes a main part 14 of generallyhollow construction and having a lower skirt portion which defines achamber 18. The upperportion 28, of the casting 14 above the transversewall 24 is also hollow and has aligned openings, one of which issurrounded by an inturned tubular portion 30 having a bearingbore 31 andextending inwardly toward the opposite open end 32 of the portion 28.Detachably mounted-on the open end 32 is 'a flanged bearing member 34having a bearing 36 in axial alignment with the bearing 31, the bearingsreceiving and rotatably supporting a spindle 38 in a manner to bedescribed in detail later. The flanged bearing member 34 is secured tothe frameby suitable means such as screws 40.

The spindle 38 is fed axially or longitudinally inthe stand so as tocarry the workpiece and move it relatively to the cutting tool which isfixed in any selected setting of the lathe. The feed mechanism or means42 ofthe present invention may be employed for this purpose and issupported on the spindle 38 and on a lead screw 44, the feed means 42being actuated in response to. the rotation of the spindle and the leadscrew being rotated by the feed mechanism (except when the latter isdisengaged therefrom as hereinafter described) and cooperating with theframe for feeding the spindle axially or longitudinally of the frameduring operation.

The spindle 38 at one end has a reduced diameter portion 46 directlyupon which the feed means 42 is mounted. ,The spindle is preferablyhollow having a small diameter'bore 48 terminating in an enlargeddiameter portion 50. The enlarged diameter portion 50 includes a n innertapered portion52 and an outer tapered portion 54, the two latterportions forming a double taper effect for receiving an arbor 56 forsuitably mountingcthe-sworkpiece. The spindle furthermore has anaxialkeyway 58 (Figs. 4 and 6) in its periphery. for rceivingakey 60which is secured in the keyway by appropriate-means such as a screw'62extending through a hole in .therkey and threaded into a tapped hole inthe spindle. :The key 60 isthusfixed in position for. cooperation withaquill 64 surrounding the spindle. The quill 64 is tubular in shape, asshown, and is sodimensioned as to havea jslidingffit with the spindle.'The quill is provided with a slot'66' extending through the wallthereof and extending asubstantial w part of. the axial lengthmf thequill for receiving the-key 60 Ifor relative sliding move- "ment'oftheflkey in'the' slotin response to the axialmovement of jtheispiiidlewhile the .quill is restrained against axial"onlongitudinal movement.The quill provides means for imparting rotation to the spindlethroughthe medium of engagement of thekey 60, with the side wall bf the'slot 66, andas the spindle is rotated, the feed means 42 produces. theaxial or longitudinal feed movementofthe spindle.

Positioned suitably on the quill 64 intermediate" its endsis acircumferential 'rib"68 having a shoulder-70 against which is butteda'ring gear 72 having worm gear teeth 74, surrounding the quill andsecured thereto by suitable means such as a screw 76 inserted through aradial hole inthering gear andthreaded into a registered threadedhole inthewallof the quill.

" The spindle-'38 'isrotated bya'driving motor 126 suita pulley122jafbelt 120' and'a pulley 116 to a shaft'88 'journaled'in bearings 92and 94. The shaft 88 carries and is driven by a worm 86 'rneshing withthe teeth 74 0f the gear 72. V

'Thedatheispprovided" with a cutting tool 168 which is'suitablymountedfor adjustment into a fixed position in cuttingrelation'with a workpiece 248 carried by the arbor 56. i

Thefeedmeans 42*which also: may be considered a power transmittingmechanism, and which as above indicated is capable of'numerousapplications, is utilized for feeding the spindle axially orlongitudinally in re sponse to rotation of-'thelatter for carrying theworkpiece longitudinallyrelative tothe normally stationary cutting tool.Theffeed rneans is of mechanical nature and is capableofan-infiniteyariation'of speed ratio. 'It is also smoothin operation'andisfnot subject to accidental 'variation inspeed ratiosuch'asimay becaused by changes in temperature as 'in 'connectionwithfothertypesoffeed means such for example a's hydraulic devices. The feed, asmentioned above,is mounted on the end of the spindle and is stabilizedby the lead screw 44' which has screw threaded connectionwiththe'frarneof the'lathe. In re sponse to the-rotation of the spindle,the lead screw 44 is.

rotated through its screw threaded,connectionwith the frame, feeds thespindle: axially or longitudinally. "The feed means42 includes thehousing'276 made upjof a main portion 278 and acap-like smallerportionf280,

the two portions having bearings and other conformations tiontherewithand' against 'sliding movement thereon.

290 and a disc element 291 having a generally axially "facing surface292 offrusto-conical shape of slight mclination relative to 'a planetransverse to the axis of the spindle. Cooperating with the frictiondisc 288 is a sliding friction disc or clutch member 294, axiallyslidable on the spindle, including a disc element 295 having a surface296 of frusto-conical.shape opposite the surface 292 and arranged sothat upon sliding of the disc -:member.:294,..the .two surfaces 292.andl296zmove relativelytoward and from each other.

jferential groove. inthe tubular portion. LCompressed between the flange300 and washer 302.is.cornpression spring means 306 madeup of apluralityof spring elements 308 each of annular form and normally offrustoconical shape arranged alternatelyoppositely with respect to eachother. ,The arrangement of the spring elements'308 establishes acompression curve: having a substantially fiat portion of considerablelength and the mechanism is so designed that the spring. means exertssubstantially constant pressure throughout the full range of ablymountedjin the chamber 18 and connected through movement of the friction'disc'294 in the operation of .the feed means. This feature establishesa constant pressure safety release condition regardless of ?.the degreeof compression of the spring means, as will be explained "more fully indetail later.

The washer 302 normally engages a spring loading cup 310 which in turnengages the inner race of a bearing 312'which1may beof any suitable typeand fitted in a recess'314 of the housing portion'280. Outwardly of thebearing 312 is a dust seal washer 316, while outwardly of the washer'316is a lock nut 318 threaded on the outer end of the spindle and securedin place by suitable means such as a set screw 320.

The variable speed feed. means incorporates a differential mechanismwhich is capable of effecting infinitely variable speed ratios, and isfor that reason smooth in operation. The differential mechanism isarranged adjacent the spindle on an axis parallel therewith and includesa' gearing 322 (Figs. 6 and 7) driven directly by the spindle throughthe medium of'the ring gear 290.

The differential. gearing is interposed in a power train from thespindle to the lead screw 44. and is adjustably controlled by a manuallymanipulable means; The differentialgearing 322 is mounted on a shaft 324which may remain stationary and is mounted inbearings 326 and 329 in thehousing and secured therein by any suitable'means. .Included in thedifferential gearing is a side gear 328.having spur teeth 330 inconstant mesh with the'ring' gear 290 on the fixed disc member 288.

The side gear 328 also has crownteeth 332 on one face.

Also mounted on the shaft 324. is a pinion. bushing 3 34' having a headportion 336 and a reduced diameter sleeve portion 338, the bushing beingfitted on the shaft 324 for rotation relative thereto. The head portion336 of thepinion bushing is provided with radially extending holes340'for mounting differential pinions or'planet gears 342 thereon. 'Thedifferential pinions. 342 are mounted on pinion studs 344 for rotationrelative thereto, the studs having outer. head portions and innerknurled reduced diameter portions 'forfrictional .retention in the holes340; The pinions 342 being freely rotatable on the studs are in meshwith the crown teeth 332.on the side gear 338. 'Asecond side gear 346 isrotatably mounted .on the reduced diameter sleeve portion of .the pinionbushmg. 338. and includes crown teeth 348 in..mesh withthe 'pinions 342,ands spur teeth 350 in mesh with a..control gear controlledldirectly.-.by...the .spindlc to. ibeudescribed later. Also, mounted onthe reduced diameter portion 338 of the pinion bushing is a spur gear352 keyed as by the shaft 324 by a feed control lever 356 also mountedon the shaft324 for rocking movement thereon.

The feed control lever 356is shown in. Figs. 2 and 4 and partially inFig. 7. In Fig. 7 a portion of the lever and the control element mountedthereon is illustrated in displaced position for the purpose ofrepresenting the action thereof since in its normal position, it wouldbehidden from view in Fig. 7.

The feed control lever 356 is pivoted intermediate its ends on the shaft324 and in one end 358 is secured a stud 360 on which is rotatablymounted a driven friction disc member 362 including a disc elementproper 364 and a spur gear 366. The disc 364 and gear 366 are preferablyintegral. The disc member 362 or at least the disc portion 364 thereofis of hardened steel for withstanding the tendency to wear to which itis subjected. The disc 364 at its periphery extends between the discsurfaces 292 and 296 and is held in friction engagement therewith by theaction of the spring means 306 in biasing the disc surfaces 292 and 296relatively toward each other as was referred to above. The gear 366 isin constant mesh with and controls the speed of. the gear 346 forcontrolling the rate of rotation of the output gear 352; This control iseffected by positioning the disc 364 inwardly or outwardly relative tothe axis of the spindle for producing various speeds of rotation of thedisc relative to the spindle, as will be brought out presently.

The feed control lever 356 being pivoted on the shaft 324 which isconcentric of course with the gear 346 enables the disc member 362 to beswung about the axis of the shaft while the gear 366 remains in constantmesh with the gear .346. Upon swinging the lever 356 (Fig. 4) thedisc364 is moved toward or from the axis of the spindle and in responsethereto is moved radially inwardly or outwardly between the discsurfaces 292 and 296. The arrangement is that, as the discs 291 and 295are rotated, rotation, is imparted thereby to the disc. 364 and underthe control of the latter, the rate of rotation of the gear 346 iscontrolled in normal operation of the device. That is, as the disc 364is moved closer to the axis of the spindle, the disc is rotated at aslower speed than when it is moved farther from the axis, and the speedof the gear 346 of the differential is regulated accordingly. As anexample-of the relationship between the various parts, the diameter ofthe disc 364 is substantially equal to the diameter of the periphery ofthe disc surfaces 292 and 296. When the periphery of the disc 364 isadjacent the outer periphery of the disc surfaces 292 and 296, there issubstantially a one-to-one ratio of the speed of rotation between therespective discs. The gear 366 is equal in diameter to the gear 290 andin the condition given the two gears mentioned, 290 and 366, rotate inone-to-one ratio.- Accordingly, the side gears 328 and 346 of thedifferential gearing rotate in opposite directions in one-to-one ratio.As a consequence, the pinion bushing 334 and gear 352 remain stationary,and since the gear 352 constitutes the output element, no rotation isimparted to the lead screw 44.

When it is desired to cause rotation of thelead screw, the feed controllever 356 is swung or rocked, as hereinafter explained, for moving thedisc 364 from the position assumed radially inwardly relative to theaxis of the spindle. This movement forces the disc 364 radially inwardlyof the disc surfaces 292 and 296, the 'spring means 306 being compressedenablingtheediscssurfaces The-differential gearing assembly justdescribed is retained axially in position on 76; and gear .352, orincreases. the speed of rotation thereof,-

to be spread accordingly. ;As the disc 364 is moved side gear 328; as aconsequence, the bushing 334 and output gear352 are rotated slowly inaccordance with the differential in speed between the gears 346 and 328.

The above description of the operation of the feed .means has to do'withthat condition wherein the lead The feed means thus provides a widerange of speed ratios between the input and output elements. The outputelement-can be regulated to zero rotation, and by providing-the desiredgear train between the output element and the lead screw, as wide arange of speed ratios as desired may thus be provided between the inputelement and lead screw. However, in the present instance,

in view of the nature of the device to which the feed means is applied,it is desired that the lead screw be rotated at a relatively low rate ofspeed.

. The feed means enables a continuous variation of speed ratios, withconsequent fine control of the speed of rota- .tion of the outputelement, which in a mechanical mecha- The operation is exnism hasnumerous advantages. treinely smooth, there are no step-by-step changesand an inherent safety feature is present in that slippage. is providedfor between the disc 364 and the disc surfaces 292 and296. If any drivenelement in the feed means beyond and controlled by the discs shouldbecome blocked, slippage will occur between the discs with the resultthat no breakage of any of the parts can result. For example, if thelead screw should become blocked and restrained against rotation, thepinion bushing 334 would remain stationary and the pinions would rotatein place. The side gear 328 would then produce rotation of the othersidegear 346 at the same speed, and the disc 364 would rotate at a speedgreater than the peripheral speed of that portion of the disc surfaces292 and 296 then engaged by the disc 364.

Another importantfeature of the present inventionis that if and whenslippage occurs, none of the parts. are

worn objectionably in such a manner as to render any of the partsinaccurate from the standpoint of operation.

The slippage that occurs between the disc 364 and disc surfaces 292 and296 produces simply a polishing action since all of the elements remainin constant rotation, and

no flats or other objectionable misshaped conformations imparted throughthe diiferential gearing to the disc 364 and the .reactive force counterto the resistance, as imposed by the spring means 396 is constant.regardlessof the setting of the disc 36'4 radially of the disc surfaces292 and 296, slippage will occur at the same predeterminedresistanceencountered.

An additional important feature of the feed means is i that resistanceencountered aids in driving the lead screw rather than hindering it."For example resistance that operates to impede rotation of the gear 346and reduce its speed of rotation, relative to the gear 328, aids indriving the lead screw in the manner mentioned. Such variation in thedifierential in speed between the gears 328 and 348 produces rotation ofthe pinion bushing 334 Therefore, L

depending upon the previous condition as to'rotation of the bushing, inthe. manner described, above in connection with the operation of thefeed means.

The torque produced on the output element is constant; regardless ofthe.speed of rotation thereof. The forces applied are exerted through gears290 and 328, and the pinions 342, and since these remain in constantradially placed positions, the torque imposed is constant throughout thespeed range. This is considered to be an important advantageparticularly in the caseof a mechanical variable speed mechanism. Theconstant torque feature is important in the use of a safety releasemeans. It is desired that safety release means yield at a definitepredetermined pointyand in the case of constant torque, it yields atthat point in all conditions of operation. A decided advantage will beseen in this arrangement, as compared with variable torque, safetyrelease means set torelease at high torque will not release properly atlow torque, and vice versa.

The speed of rotation of the output element will remain constantaccording. to the setting of the mechanism regardless of any changes oftemperatures, which also is an important advantage and overcomes anobjection in this respect encountered in the case of hydraulicequipment.

The adjustable setting of the feed meansfor producing the desired speedratio is accomplished by means of a feed adjusting screw 368 (Figs. 4and. 5) which includes a shaft 370 rotatably mounted in a bearing 372formed in the housing portion 278. The shaft 370 is restrained againstlongitudinal movement by means of a pin 374 fitted in a transverseopening in the housing and positioned in a circumferential groove 376 inthe shaft. The inner'end of the shaft 370 is provided with a helicalgroove 378 of appropriate lineal length in which is received a pin 380secured in the end 382 of the feed control lever 356 opposite theend 358in which the disc member 362 is mounted. Upon rotation of the shaft 370the pin 380 follows the helical groove and produces the desired swingingmovement of the feed control lever 358 for moving the disc 364 towardand from the axis of the spindle in the manner and for the purposedescribed above.

The outer end of the shaft 370 projects out of the bore 372 where it hasa reduced diameter portion 384 forming a shoulder 386. A dial 388 ofsuitable construction is fitted on the reduced end portion of the shaftin' abutment with the shoulder 386 and secured on the shaft by suitablemeans such as a set screw 390. The dial 388 includesa flanged portion392 on which are provided suitable indicia markings 394 (Fig. .1)cooperable with a suitable indicator mark on a projection 396 on thehousing adjacent the periphery of the dial. The inner surface of thedial is provided with a circumferential groove 398 in which is receiveda stop pin 400 secured in the housing and projecting therefrom. Anotherpin 401 fitted in a hole in the dial extends into the groove forengagement with the stop pin 400 for limiting the extent of rotation ofthe dial in both directions. Upon loosening the set screw 390, the dialmay be adjusted to the desired setting relative to the shaft after whichthe set screw is tightened, enabling the dial to be set to properlyindicate the setting of the feed means.

The remaining portion of the drive in the feed means 42 between themechanism described above and the lead screw 44 is shown in- Figs. 4, 5and 6. The lead screw 44 has an unthreaded shaft portion 402 mounted ina bearing 404 of the housing and extends parallelwiththe axes of theshaft 324 and spindle. inwardly of the bearing 404 a jaw clutch element406 ismounted on the. shaft portion 402 and secured thereto'by suitablemeans such as, for example, apin 408.

Cooperating with the jaw clutch element 406 is a sliding jawclutchelement 410 mounted on the shaft portion 402 for] rotationrelative thereto and limitedmsliding,

' a diametrical bore 416 in the shaft and biased outwardly which is inconstant mesh with the output gear 352 of.

the feed means, referred to above and controlled by the differentialgearing 322. The-gear 420 is of lesser axial extent than the gear 352 toenable the sliding movement of the gear 420 relative to the gear 352 inresponse to shifting of. the clutch element, whereby the gears remainconstantly in mesh. The clutch element 410 is provided with acircumferential groove 422 for receiving an element of the clutchshifter as will be referred to later.

The shaft portion 402 is provided with a reduced diameter extremity 424on which is fitted a miter gear secured thereto as by a diametrical pin428, the hub portion of the gear being suitably received in a recess ofthe clutch element 410. A spacer bushing 430 is interposed between themiter gear 426 and the-bearing portion 432 in the housing in which theextreme end portion of the shaft is supported.

.Manual means is provided for rotating the lead screw 44 which includesa shaft 434 suitably supported in bearings in the housing and disposedtransversely to the lead screw 44. On the inner end of the shaft 434 isfixed a miter gear 436 in mesh with the miter gear 426,

while the opposite end of the shaft which projects out of the housing isprovided with a handwheel 438 for manual rotation of the shaft andconsequent rotation of the lead screw 44. The handwheel 438 may beutilized when the clutch 406, 410 is declutched for adjusting thespindle longitudinally to initially set the workpiece according to thesetting ofthe cutting tool. When, however, the clutch is in clutchedcondition the lead screw is operated by the spindle through the feedmeans, and the spindle is fed longitudinally in response to its rotationand at a rate according to the setting of the feed means. i

The means for clutching and declutching the clutch is arranged forautomatically declutching it when the cutting operation is completed.The means is in the form of a clutch shifter having a shaft 440 (Fig. 4)suitably mounted ina bore 442 and preferably positioned near thevertical. On the inner or lower end is a clutch shifter 444 having alaterally extending leg 446 in the end of which is mounted a pin 448extending into the groove 422 in the sliding clutch element 410. On theouter or upper end of the shaft 420 is a handle 450' suitably securedto'the shaft as by a knurled arrangement or other convenient means. Thehandle has a manipulable portion 452 arranged for convenient grasping bythe hand and in the under surface of the handle is a hole receiving apin 454, the other end of which is inserted in a hole in a rod 456. Therod 456 is supported at one end on the housing of the feed means and itsother end extends throughan opening in the flanged portion of the member34 on the frame of the lathe. Adjustably s'lida'bly mounted on the rod456 is acollar 458 provided with a set screw 460 arranged so thatthecollar maybe slid along the rod and fixedly set inany adjusted position.The lead screw 44 has threaded engagement in a threaded hole in themember 34, at

I formed on the member.

9 The clutch 406, 410 may be clutched and declutched manually bymanipulation of the clutch shifter handle 452 in response to which theleg 446 on the clutch shifter swings and thereby shifts the clutchelement 410 into the clutch in the feed means is declutched. I Thisposition is that in which the declutching operation is to beacoomplished when an automatic operation is performed. With the partsset according to the above, the collar 458 is slid along the rod 456 tothe position wherein it engages the frame of the lathe. The set screw460 is then tightened and the collar remains in fixed position. Thespindle is then run back to the position desired for starting thecutting operation (as in Fig. 1), whereupon the clutch is shifted toclutched position manually by manipulating the handle 452. The lathe maythen be set in operation and in response to the location of the spindle,the latter is fed axially or longitudinally (to the left of Fig. 1) bymeans of the feed means 42. The movement ofthe feed means causes the rod456 to be slid with it, through the medium of the shifter handle 452.Upon engagement of the collar 458 with'the frame of the lathe, movementof the rod 456 is checked and continued movement of the feed meansrelative to the rod causes the rod to swing the clutch handle 452 andshift the clutch to declutched position. Thereafter any continuedrotation of the spindle in ineffective for producing a longitudinal feedmovement thereof. The machine may then be shut off and the workpiecedismounted therefrom.

From the foregoing it will be seen that the feed mechanism of thepresent invention is capable of wide application where it is desired toprovide for a continuous variation in the speed ratio between a drivingshaft and a driven shaft.

I claim:

1. Friction drive means for cooperation with a power input shaft andgear, and a power output shaft and gear ripherally engaging frictiondisc members, and differential gear means including a pair of maingears, a plurality ofplanetary gears, each meshing with both of saidmain rotation about their axes and for rotary movement about saiddifferential gear shaft, one of said main gears meshing with said powerinput gear, one of said friction disc members being secured to saidpower input shaft,

the other of said friction disc members being mounted on a fourth shaftand frictionally engaging said one friction disc member, a geardrivingly connected to said other friction disc member and meshing withthe other of said main gears, said carrier including a sleeve rotatableon said differential gear shaft and extending through and beyond one ofsaid main gears, said last mentioned main gear being rotatable on saidsleeve, and a gear secured to the free end of said sleeve and meshingwith the power output gear, said fourth shaft being mounted for pivotalmovement about said differential gear shaft whereby said friction discsmay be moved relatively toward and away from each other.

2. The friction drive means of claim 1 wherein said one friction discmember comprises two elements having facing surfaces sloping radiallyoutwardly away from each other and receiving the periphery of said otherfriction disc member therebetween, one of said elements being rigidlysecured to said power input shaft and the other of said elements beingslidable thereon, and spring means uring said other element toward saidone element.

References Cited in the file of this patent UNITED STATES PATENTS917,463 Larsen Apr. 6, 1909 1,455,093 Roebuck May 15, 1923 1,713,873Jeune May 21, 1929 1,730,797 Zoller et a1. Oct. 8, 1929 2,233,967,Wellton Mar. 4, 1941 2,395,586 Scott Oct. 7, 1942 2,583,496 RougelotJan. 22, 1952 2,659,245 McLaren Nov. 17, 1953 FOREIGN PATENTS 730,233France Aug.9, 1932

